If you attend a school on an ROTC scholarship and are accepted at a SA after your freshman year, you are not obligated to stay with the ROTC scholarship. You can attend a SA with no issue. Actually you are free to walk after your freshman year for any reason. You incur a service and obligation once you start your sophomore year in ROTC. I have heard of ROTC folks getting accepted even after their sophomore year. I believe they had to apply for a waiver to be released, but from everything I have gathered, these have been granted.